1. Field of the Invention
This invention relates generally to data cards, and more particularly, to inductive signal transfer devices of data cards.
2. Description of the Prior Art
There have been developed data cards which are carried on the person for use as a credit card or the like, and which include information data record mediums such as magnetic stripes or memory mediums such as semiconductor memories, adapted to interact with circuitry in a receptor in which the data card is placed so as to operate on information data stored in the data record mediums or the memory mediums of the data card. Recently, the there has been a demand for data cards with a capacity to store a greater and greater amount of information data. For responding to the increasing demand, there have been developed data cards which include a semiconductor device such as the semiconductor memory instead of the magnetic stripe. The data cards of such type are usually provided with another semiconductor device such as a micropcomputer adapted to process information data, together with the semiconductor memory. As is well known, the semiconductor devices are generally fabricated in the form of an integrated circuit (referred to as an IC hereafter). The data cards which comprise the semiconductor devices are referred to as IC cards.
Conventionally, the IC cards are equipped with connectors (referred to as card-connectors hereafter) made of conductive material for transferring an information data and/or a drive signal for activating circuits in the IC cards. The card-connectors are adapted for electrically coupling with other connectors (referred to as reader-connectors hereafter) provided in an information data reading/writing apparatus for processing the information data. The apparatus is generally called a card reader. Thus, the work "card reader" is used in this specification for meaning an apparatus which is provided for writing information data into the data cards such as the IC cards or cards with magnetic stripes (referred to as magnetic cards hereafter) and/or reading out information data therefrom. The card-connectors of the IC cards mechanically contact the reader-connectors equipped in the card reader.
The conventional IC cards have a drawback in which the mechanical contacts between the connectors of the IC cards and the card readers, i.e., the card-connectors and the reader-connectors are inferior in reliability. For example, the card-connectors, which come into mechanical contact with the reader-connectors in the card readers, may eventually become worn away. Thus, contact errors are sometimes caused between the card-connectors and the reader-connectors. If the top surface of the card-connector is made somewhat lower in level than other parts of the IC card, a contact error can be caused by dust which may gather on the lowered surface of the card-connector.
Furthermore, the conventional IC cards have another drawback. That is, the the conventional IC cards cannot be used with the card readers which are adapted for use with the conventional magnetic cards.
The conventional IC cards of such type have still another drawback as follows. If the card-connectors of the IC card come into contact with any substance, such as clothes made of synthetic fibers, which is charged with a lot of static electricities, the semiconductor devices such as the microcomputor and the memory are liable to be damaged by the static electricities.
Then, there has been proposed another signal transfer system due to an electro-magnetic coupling. In the system, both the IC card and the card reader are equipped with electro-magnetic transducers, respectively, which are provided for electro-magnetically coupling between each other. Thus, information data are transferred between the IC cards and the card readers, without relying upon the mechanical contacts between connectors. The IC cards equipped with such an electro-magnetic transducer are free from the drawbacks of the prior art IC cards.
The conventional electro-magnetic transducer for the IC cards is formed to a coil configuration by a thin film conductor or a sheet conductor. A card reader adapted for the IC cards also is equipped with a similar electro-magnetic transducer, i.e., a type of the coil configuration. For the conventional data cards and the card readers equipped with electro-magnetic transducers of such type, a reference is made to the U.S. Pat. No. 4,605,844.
The IC cards equipped with the electro-magnetic transducers are desired to be compatibly available for conventional card readers adapted for magnetic cards. The card readers for the magnetic cards (referred to as magnetic card readers hereafter) are equipped with an electro-magnetic transducer of another type, e.g., a magnetic head. As is well known, the magnetic head is comprised of a ring-shape core with a gas and a coil wound on the core.
The conventional IC cards equipped with the coil type electro-magnetic transducer are insufficient for being in conformity with the conventional magnetic card readers. That is, the coil type electro-magnetic transducer fails to transfer a sufficient amount of magnetic flux between the magnetic head type electro-magnetic transducer of the conventional magnetic card readers.
Furthermore, the conventional IC cards equipped with the coil type electro-magnetic transducer still have a drawback. That is, the electric-magnetic transducer used in the conventional IC cards is easily affected by a noisy magnetic flux other thant he magnetic flux applied from the card readers adapted for the IC cards.